Just purchased a Helix 10 Mega Chirp SI GPS. In reading and watching the enclosed video it states you have to have a clean site line from left to right for your SI to work properly. How much clearance between the lower unit of your OB and the transom of you boat do you need? the entire length of the transducer? If that is the case I fear I may need to make some boat modifications to accommodate the transducer. However what are my options? Any thoughts, ideas or experience would be greatly appreciated.

I am running a 150 Yamaha HPDI and mounted the transducer Starboard of the lower unit. I turned the motor all the way to that side and trimmed all the way in then mounted the transducer so there was a 1/2" of clearance and the lower unit then could not hit the transducer. I do have to trim out a little to get a clear view to port but I never run trimmed full in anyway. Just make sure you have fore and aft. Port and Starboard level at the boat load and speed you will be using it at the most. There are good videos on how to best do that. Don

I am running a 150 Yamaha HPDI and mounted the transducer Starboard of the lower unit. I turned the motor all the way to that side and trimmed all the way in then mounted the transducer so there was a 1/2" of clearance and the lower unit then could not hit the transducer. I do have to trim out a little to get a clear view to port but I never run trimmed full in anyway. Just make sure you have fore and aft. Port and Starboard level at the boat load and speed you will be using it at the most. There are good videos on how to best do that. Don

Thanks Don... so you trim out a little when scanning to ensure your port side of the scan?

That kinda makes since because you're only going to be going 5 or 6 miles an hour at best when scanning.

With ice still on the lake I have no way of testing or tweaking at the moment.

Once you trim out the motor the scan instantly goes out the distance you set? Is that how you know you have no obstructions?